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System Architecture Lab 1 An Analysis of Fault Isolation in Multi-Source Multicast Session Network Research Workshop 2003. 8. 28 Heonkyu Park

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Presentation on theme: "System Architecture Lab 1 An Analysis of Fault Isolation in Multi-Source Multicast Session Network Research Workshop 2003. 8. 28 Heonkyu Park"— Presentation transcript:

1 System Architecture Lab 1 An Analysis of Fault Isolation in Multi-Source Multicast Session Network Research Workshop 2003. 8. 28 Heonkyu Park Korea Advanced Institute of Science and Technology

2 System Architecture Lab 2 Table of Contents 1.Motivations / Problem Definition 2.Background 3.Analysis 4.Issues 5.Candidate Model 6.Simulation Results 7.Conclusion References

3 System Architecture Lab 3 Before we start… Terminology –Unicast : to a single receiver –Multicast : to a specific subset of receiver single-source : only one source in a session (one-to-many multicast) multi-source : many sources in a session (many-to-many multicast) –Fault Detection –Fault Isolation Fault Detection Hmm… Fault is in somewhere… : perceiving the fault in somewhere in the network OK! I found the Fault! Fault Isolation : locating the fault that on-tree router or link which is the origin of a fault.

4 System Architecture Lab 4 Motivation 1.Network monitoring is necessary to detect and discover of network problems. 2.Some participants in multicast experience severe packet loss. 3.Fault detection / isolation approaches in multicast are focused on single-source network. Obtained using Rqm [rqm] tool New model for fault isolation in multi-source multicast is needed. / Problem Definition 4.In multi-source multicast, little work has been done for fault isolation. 5.Straightforward reuse single-source solution is not sufficient for large number of multi-source multicast.

5 System Architecture Lab 5 receiver source send to a multicast session receiver Background 1.IP Multicast 2.Multi-Source Multicast Applications 3.Challenges of Multicast Monitoring 4.Needs for Multicast Fault Isolation 1.IP Multicast Multicast Packets When fault occur routing path is changed when a fault is occurred.

6 System Architecture Lab 6 Multi-Source Multicast Applications 1.Networked virtual environments 2.Synchronized resource like database updates 3.Distributed or parallel concurrent processing 4.Large-scale distributed military simulation 5.Peer-to-peer multicast file transfer model 6.Large-scale multimedia conference 7.Large-scale replicated database 8.Cooperative web cache protocols 9.Shared editing and collaboration 10.Interactive distance learning 11.Network games or chatting 12.and more… Number of Receivers Number of Senders Streaming Content Distribution 101,000 1 1,000,000 10 1,000 1,000,000 Collaboration Tools Games Distributed Information Systems Peer-to-Peer Applications Group Size [LN01]

7 System Architecture Lab 7 Multicast Monitoring Tools [SA01] Management, Debugging and Modeling via Active / Passive Monitoring Monitoring Mahs Study Yajniks Study Handleys Study MINC * * : can be used for active monitoring Debugging ModelingManagement mrmap mrinfo mrdebug rtpmon mtrace mwatch mlisten Dr. Watson MultiMon mhealth RouteMonitor MantaRay NIMI * mantra sdr-mon Otter MRM * mwalk HPMM mstat mview mrtree GDT NetIQs Chariot * mmon SNMP_NG Time ~1992 ~1997 ~2000 recent research work

8 System Architecture Lab 8 Needs for Multicast Fault Isolation 1.Monitoring of multicast network has become a crucial for maintaining the multicast operations –since the delivery service in multicast is more complex than in traditional unicast networks –Supervising multicast traffic is more difficult problem as each multicast tree involves multiple hosts with correlated, simultaneous faults. 2.There are various reasons causing multicast fault. –session announcement problem, reception problem, multicast router problem, congestion and rate-limiting problems, multicast routing problem, etc. [TA00] 3.It is not easy work even in single-source multicast, to say nothing of multi-source multicast.

9 System Architecture Lab 9 Analysis on Single-Source Approach Only for fault detection 1.MRM (Multicast Reachability Monitoring) [SA01] active probing from a test sender(TS) to a test receiver(TR) by MRM manager 2.SMRM (SNMP-Based MRM) [AT02] SNMP-based approach defined several MIB for multicast monitoring Both detection and isolation 3.HPMM (Hierarchical Passive Multicast Monitoring) [WL00] passive monitoring scheme that agents are organized in a hierarchy and communicate with each other using unicast 4.MTR (Fault Isolation in Multicast Tree) [RGE00] receiver-driven method using IGMP multicast traceroute Most approaches up to now focused on single-source multicast.

10 System Architecture Lab 10 MRM (Multicast Reachability Monitor) [SA01] - Description Step 2: TS Transmits Step 1: Mgr Configures TS(s) and TR(s) Step 3: TR(s) Monitor Group Transmission Step 4: Mgr Collects and Displays TR Reports RouterEnd-Host Manager Agent Communication TS TR2 TR1 MRM Manager TR3 R3 R1R2 R4R5 R6 TS: Test sender TR: Test Receiver

11 System Architecture Lab 11 SMRM (SNMP-Based MRM) [AT00] - Description smrmMIB Group in Extended MIB II

12 System Architecture Lab 12 HPMM (Hierarchical Passive Multicast Monitor) [WL00] - Description Foreign domain 1 source 1 Foreign domain 2 source 2 Local domain A B C DE group 2 group 1 Each node knows exactly which upstream agent to notify in case of a fault occurrence. Node D has only one parent for both multicast groups 1 and 2, which is node B Node E defines a parent agent in B for group 1 and a parent agent in C for group 2. 1 1 1 1 2 2 2

13 System Architecture Lab 13 MTR (Fault Isolation in Multicast Tree) [RGE00] - Description Source R b R c R b R a R c Before R a Isolated Fault Region After common ancestor router of Ra & Rc : Fault

14 System Architecture Lab 14 Comparison on Related Works Active/ Passive Single- sourceMulti-source Remarks DetectIsolateDetectIsolate MRM Active test session SMRM Passive SNMP-based HPMM Passive child-parent relationship MTR Active IGMP mtrace No suggested approaches are sufficient for fault isolation in multi-source multicast network.

15 System Architecture Lab 15 Message Complexity of Current Approaches 1.Network overload exponentially increased by extending number of members As extend member size, mtrace request packets and mtrace reply packets are excessive. 2.Simulation result by ns-2 tree topology: 100 nodes, out-degree : 3 number of members : 5 ~ 60 (increased by 5) 5 times average calculation 3.Thus, it needs different strategy to handle multi-source multicast fault detection and isolation.

16 System Architecture Lab 16 Issues 1.Application Characteristics 2.Message Complexity 3.Fault Isolation Error 4.Scalability 5.Deployment Conferencing ApplicationBroadcasting Application Performance requirements Require low latency and high bandwidth interested in bandwidth, latency is not concern Losstolerate lossrequire reliable data delivery Session lengthlong lived, over 10 minshort-lived Group characteristics Dynamic and small groupsrelatively static Source transmission patterns multiple sourcesa single static source 1.Application Characteristics Comparison on two applications [CRSZ01]

17 System Architecture Lab 17 Issues for Multi-Source Multicast Fault Isolation 1.Message Complexity –Message complexity will be main concern. –Not to increase linearly, but to logarithmic not O(N), but O(logN) or O(1) 2.Fault Isolation Error –Should be same or decreased compared to previous approach. –No sudden computation overload to isolate faults –near-realtime fault detection and isolation function 3.Scalability –not effected with the number of members –dynamic member action like join / leave actions 4.Deployment –should be easily deployable not depend on protocols and techniques. size of members message complexity not good Acceptable

18 System Architecture Lab 18 Candidate Model Goal : Isolate the fault promptly and accurately using efficient and scalable approach in the multicast network when the fault is occurred. Basic Idea : member grouping not let all member send probe 2.there exists shared path from local member to other members 3.make maximum use of shared information 4.only group leader send probe for fault isolation to other group leaders Benefits 1.reduce message complexity 2.scalable since not depend on size of members

19 System Architecture Lab 19 Draft Model 1.Each group select a group leader. 2.Group leader manages its member and sends probes for fault isolation. 3.Not send to all other group leaders, but send just common ancestor router with other group leaders. A1 A2 A3 B1 B2 C1 D2 Group AGroup B Group C Group D D1

20 System Architecture Lab 20 Member Grouping the members are grouped –simply, boundary within border router –need to find a way to make a group bigger since the number of group can be still large the members in a group know their group leader –group leader send a probe to group member periodically i-am-leader packet know group leader exist –newly joined member send i-am-leader packet in a group using multicast scoping –if no response, it becomes the leader. –if somebody send i-am-leader packet, consider there is a leader. border router one group group leader

21 System Architecture Lab 21 Group Leader Action Lists 1.Managing members in group –use i-am-leader to control group member –you-are-leader packet when leave 2.Fault Isolation –primarily function for group leader –exchange among other group leaders 3.Group leader announcement –It is not easy work to announce and to find out the group leaders

22 System Architecture Lab 22 Simulation Results Overview –Simulated a simplified protocol using ns-2 simulator –Random graph by GT-ITM –Average value after five time simulations –Compared with best approach among related works Results –All-member-based (best-performance) –Group-leader-based –reduced the message complexity 68%

23 System Architecture Lab 23 Conclusion 1.It is important to locate the fault in a network. 2.Little work has been done for fault isolation even in detection in multi-source multicast. 3.In multi-source multicast fault isolation, message complexity is main concern. 4.One candidate approach is a group-based architecture to locate the fault in a multi-source multicast session. 5.Simulation results show group-based approach reduced the message complexity as amount of 68% than the best performance approach among other ones. 6.However, group-based approach is not fully enough for scalability reason, etc.

24 System Architecture Lab 24 Future Works Need more efficient approach for message complexity. Possible model is suppressed one-way probing mechanism. –Source sends a special packet to multicast group. –All internal router records its routing information in the special packet. –Without packet suppression, implosion problem will be occurred. –Receiver compare to check whether routing path was changed. Simulation results show that this suppressed one-way probing is well suit for multi- source multicast network. Several things to elaborate… Any comment will be appreciated.

25 System Architecture Lab 25 References [AT02] E. Al-Shaer and Y. Tang, SMRM: SNMP-based multicast rechability monitoring, in IEEE/IFIP Network Operations and Management Symposium (NOMS) 2002, Florence, Italy, April 2002. [CRSZ01]Yang-hua Chu, Sanjay G. Rao, Srinivasan Seshan and Hui Zhang, Enabling conferencing applications on the Internet using an overlay multicast architecture, in ACM SIGCOMM 01, San Diego, California, August 2001. [LN01] J. Liebeherr and M. Nahas, Application-layer multicast with Delaunay Triangulations, Global Internet Symposium, IEEE GlobeCom 2001, San Antonio, Texas, November 2001. [RGE00] A. Reddy, R. Govindan and D. Estrin, Fault isolation in multicast trees, In Proceeding of ACM SigComm 2000, Stockholm, Sweden, Aug. 2000. [Rqm] C. Perkins, RTP Quality Matrix, (RTP Quality Matrix), [online], http://www- (Accessed: 7 March 2003). [SA01] K. Sarac and K. C. Almeroth, Supporting multicast deployment efforts: A survey of tools of multicast monitoring, Journal of High Speed Networking--Special Issue on Management of Multimedia Networking, vol. 9, num. 3/4, pp. 191-211, March 2001. [TA00] D. Thaler, B. Aboba, Multicast Debugging Handbook, Internet draft, draft-ietf- mboned-mdh-*.txt, Internet Engineering Task Force (IETF), November 2000. [WL00] J. Walz and B. N. Levine, A hierarchical multicast monitoring scheme, In 2nd International Workshop on Networked Group Communication, Nov. 2000.

26 System Architecture Lab 26 Thank you. Question? Comment?

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